Difference between revisions of "Histology Glossary - P"

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'''Pacchioni''',''' '''Antonio. 1665-1726 Rome & Tivoli anatomist;''' '''Pacchionian bodies = arachnoid granulations (1705), q.v.
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'''pachymenix''' G.  ''pachys '' = thick +  ''menix '' = a membrane; the dura mater.
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'''Pacini''', Filippo. 1812-1883 Pisa & Florence anatomist; lamellated (onion-like) corpuscles of Vater-Pacini in skin (1840); tendon sheaths.
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'''palate '''L.  ''palatum '' = roof of mouth.
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'''palisade''' L.  ''palus '' = stake; like a fence of stakes.
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'''palmate folds '''cf. plicae palmatae.
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'''palpebral''' adj. L.  ''palpebra '' = eyelid, from L.  ''palpitare '' = to move quickly.
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'''pampiniform '''adj.''' '''L.  ''pampineus '' = full of vine tendrils +  ''forma '' = shape; a tangled mass of veins in spermatic cord.
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'''pancreas''' G.  ''pan '' = all +  ''kreas '' = edible flesh; a sweetbread (though less of a delicacy than the thymus); intestinal exocrine & endocrine gland.
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'''pancreatic islets '''small islands or''' '''clusters of endocrine cells in pancreas; cf. Langerhans.
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'''panniculus adiposus '''L. = a little piece of cloth, a rag + L.  ''adeps '' = fat (adiposus is a L. corruption); the hypodermis (Berengarius, 1524).
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'''Paneth''', Josef. 1857-1890 Breslau & Vienna physiologist; P. cells (1887) = eosinophilic cells at base of intestinal crypts of Lieberkühn.
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'''papilla''' '''(-ae)''' L. = a teat, a nipple; a nipple-like projection, e.g., on the tonge (Malpighi, c. 1670; cf. circumvallate, filiform, foliate, fungiform, vallate); duodenal papilla (containing duodenal ampulla); optic papilla; renal papilla (Berengarius, c. 1480-1550).
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'''papillary '''adj.''' '''L. "; of the most superficial layer of the dermis, containing fine collagen fibres immediately under the epidermis; of cardiac muscle fibres that form eminences on the inner surface of the ventricles.
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'''para-''' G. = beyond, beside, near.
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'''paradidymis '''G. " +  ''didymos '' = testicle; remains of mesonephros situated on the spermatic cord above the epididymis= organ of''' '''Giraldès, q.v.; also = organ of Waldeyer.
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'''paraganglion (-ia) '''G. " +  ''ganglion '' = a swelling; clumps of chromaffin tissue scattered alongside sympathetic nerves in thorax and abdomen; cf. Zuckerkandl.
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'''parakeratin '''G. " +  ''keras '' = horn; a type of keratin formed in superficial cells at sites of abrasion and rapid epithelial renewal, e.g., gingiva, tongue, tonsillar crypts, palate.
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'''parametrium''' G. " +  ''metra '' = womb, uterus; loose, fatty connective tissue in the broad ligament around uterus.
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'''parathyroid '''G. " +  ''thyreos '' = a shield (cf. thyroid gland); gland lying "alongside" the thyroid.
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'''parenchyma''' G. " +  ''enkeim '' = to pour in; the essential functional cells of an organ as opposed to its stroma, q.v. (NB. the accent is on the "e", not the "y").
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'''paries (-ities) '''L.  ''paries '' = a wall; cf. body wall around a coelom q.v.
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'''parietal''' adj. L.  ''parietalis '' = relating to walls; the outer region or wall as opposed to visceral.
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'''paroöphoron '''G.  ''para '' = beside +  ''öon '' = egg +  ''phoros '' = bearing; minute tubules of the mesosalpinx lying adjacent to the uterine tube, derived from caudal part of embryonic mesonephros.
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'''parotid '''G.  ''para '' = beside +  ''otos '' = of the ear; a salivary gland.
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'''parous''' L.  ''pario  ''= I bear (children).
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'''pars '''L. = a part; a part of an organ, or structure, e.g., pars iridica retinae; pars nervosa; pars distalis, etc.
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'''PAS''' <U>p</U>eriodic <U>a</U>cid &amp; <U>S</U>chiff's reagent; histochemical stain for carbohydrates involving production of aldehyde groups by initial treatment with periodic acid, then reaction of these groups with Schiff's reagent to produce a magenta colour.
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'''pearl ''' 1. a concretion formed around a grain of sand, etc.; 2. a small tough mass of material, e.g., a keratin pearl, an enamel pearl, a pearl of mucus in sputum.
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'''pectinate '''adj. L.  ''pecten '' = a comb; musculi pectinati = muscular bands passing forwards from crista terminalis in wall of right atrium (including the crista, resembles a comb).
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'''pedicel''' L.  ''pediculus '' = a little foot, dim. L.  ''pes ''; stem attached to growing process; pedicles of podocytes in renal glomerulus.
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'''pedicle '''L.  ''pediculus '' = a little foot (dim. of L.  ''pes '' = a foot); stem or connecting stalk of a tumour; bony process connecting the lamina of a vertebra to its body; renal pedicle = renal "stalk".
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'''pellucidum''' L.  ''per '' = through +  ''lucere '' = to shine; translucent; e.g., zona pellucida of ovarian follicle; septum p. of brain.
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'''pelvis''' L. = a basin.
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'''penicillar''' adj. L.  ''penicillum '' = a paint-brush, from L.  ''penna '' = a feather; branching into many short segments, as in the penicillar arterioles of the spleen
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'''penis '''L. = a tail.
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'''pepsinogen '''G.  ''pepis '' = digestion +  ''gennan '' = to produce; a precusor of pepsin = enzyme that aids digestion.
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'''peri-''' G. = around, about.
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'''pericardium''' G. " +  ''kardia '' = heart; of two types: visceral (covering the heart) and parietal (lining the pericardial sac).
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'''perichondrium''' G. " +  ''chondros '' = granule, gristle, cartilage; connective tissue and cellular layer surrounding cartilage.
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'''pericyte''' G. " +  ''kytos '' = hollow vessel; mesenchymal cell adjacent to capillaries.
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'''perikaryon''' G. " +  ''karyon '' = nucleus; body of a nerve cell surrounding its nucleus; soma, q.v.
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'''perilymph '''G. " + L.  ''lympha '' = clear fluid; a bastard term (from G. &amp; L.) for fluid in bony labyrinth surrounding the membranous labyrinth; cf. endolymph.
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'''perimysium''' G. " +  ''mys '' = muscle; connective tissue around a muscle fascicle.
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'''perineurium''' G. " +  ''neuron '' = sinew; a lamellated sheath of connective tissue and cells around a nerve fascicle.
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'''periodontal ligament '''or''' membrane '''G. " +  ''odons '' = tooth; fibro-elastic tissue (including Shapey's fibres) joining the tooth to its alveolar socket in the bone.
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'''periodontium '''G. " ; all the tissue around the root of a tooth.
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'''periosteum''' G. " +  ''osteon '' = bone; fibrous membrane covering bone, attached to bony matrix by Sharpey's fibres.
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'''peripheral nervous system '''nerves and nerve cells outside the central nervous system; abb. PNS.
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'''peristalsis''' G. " +  ''stalsis '' = a contraction, from  ''stellein '' = to constrict; progressive contractile wave along body tubes (Culpeper, 1655); adj. peristaltic.
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'''peritoneum '''G.  ''peri =  ''around + '' teinein '' = to stretch around; membrane stretched around the lining of the abdominal sac and ensheathing some viscera; adj. peritoneal.
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'''Perls''', Max, 1843-1881 German pathologist; Perls' test for hemosiderin using the Prussian blue reaction/stain.
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'''Peyer''', Johann Konrad. 1653-1712 Schaffhausen, professor of Logic, Rhetoric &amp; Natural Science; P.'s patches = aggregated lymphatic nodules in terminal ileum (1673).
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'''phagocytosis''' G.  ''phagein '' = to eat +  ''kytos '' = cell +  ''osis '' = a condition of; process by which a cell engulfs foreign particles, dead material, etc.
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'''phalangeal ''' adj. G.  ''phalanx '' = a band of soldiers (a Greek army division in battle order); phalangeal cells = sustentacular cells in organ of Corti whose processes extend upwards between the hair cells like fingers; Deiters, q.v.
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'''pharynx''' G. = throat; adj. pharyngeal (? G.  ''pharanx '' = a cleft, chasm).
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'''pheomelanin '''G.  ''phaios '' = dusky red +  ''melas '' = black; pigment found in red hair.
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'''phlegm '''G. phlegma = thick mucus; one of four humours of early physiology; thought to be a discharge from brain; cf. pituitary.
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'''Phloxine''' red cytoplasmic dye.
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'''photoreceptor '''G.  ''phos '' = light + L.  ''recipio '' = I receive; bastard term for light-sensitive cells in retina.
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'''physic '''G.  ''physikos '' = natural; the art of medicine.
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'''pia mater''' L.  ''pius '' = soft, faithful (L.  ''pietas '' was one of the cardinal virtues) +  ''mater '' = mother; delicate vascular membrane which adheres to surface of brain and spinal cord, faithfully following their contours.
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'''picric acid''' a yellow dye.
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'''pilomotor''' L.  ''pilus '' = a hair +  ''motor '' = mover; causing hair movement; cf. arrector pili.
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'''pineal '''L.  ''pinea '' = pine cone; cone-shaped gland of the brain; cf. conarium.
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'''pinocytosis''' G.  ''pinein '' = to drink +  ''kytos '' = cell +  ''osis '' = a condition of; process by which a cell takes in droplets of fluid.
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'''pituitary '''L.  ''pituita '' = phlegm, snot; gland at base of brain thought to be responsible for nasal secretion, via perforations in cribriform plate of ethmoid (Vesalius, c. 1560).
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'''placenta '''L. = a flat cake, from G.  ''plax ''- = flat- ; (Ge.  ''Mutterkuchen '' = "mother-cake" = placenta).
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'''plasma''' G. = a thing formed; liquid component of lymph, blood; NB. plasma membrane = cell membrane.
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'''plasmodium '''G. " +  ''-oeides '' = like; a continuum of protoplasm in which many nuclei are embedded, e.g., placental plasmodium = syncytiotrophoblast.
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'''plasmolysis '''G. " +  ''lysis '' = solution; shrinkage of a cell due to osmotic pressure.
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'''platelet''' OF.  ''plate '' = flat; small, non-nucleated discoids in circulating blood derived from fragmentation of megakaryocytes.
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'''pleomorphic''' G.  ''pleon '' = more +  ''morphe '' = form; varying in shape and size.
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'''pleura''' '''(-ae)''' G. = rib, side; serous membrane covering lungs and lining thorax; parietal and visceral pleurae.
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'''plexus''' '''(-i)''' L. = a braid; a woven network of linear structures, especially nerves.
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'''plica''' '''(-ae)''' a corruption from L.  ''plicare '' = to fold; in13th century a scalp infection endemic in Poland was called  ''plica polonica '' (Polish plait); any kind of fold.
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'''plicae circulares '''L. = circular folds; actually transverse folds that are not circular in small intestine = valves of Kerckring, q.v.
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'''plicae palmatae '''L. " +  ''palmatae '' = like palm trees; flat mucosal folds like palm fronds in uterine cervical canal.
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'''podocyte''' G.  ''podos '' = foot +  ''kytos '' = hollow vessel (cell); cell in renal glomerulus with many feet (foot processes) and pedicels.
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'''-poiesis''' G. = making or producing; suffix as in haemopoiesis, leucopoiesis.
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'''polar body '''the''' '''smaller daughter nucleus of a fertilised dividing ovum.
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'''polkissen''' Ge. = pole cushion; extraglomerular mesangial cells at vascular pole.
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'''polychromatophilic''' G.  ''polys '' = many +  ''chroma '' = colour +  ''philein '' = to love.
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'''polymorphonuclear ('''abb.''' polymorph)''' adj. G. " +  ''morphe '' = form; having a nucleus with different shapes (multiple lobes), e.g., a neutrophilic leucocyte.
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'''polyploid '''G. " +  ''-oeides '' = form of; G. = manifold; having several sets of chromosomes; cf. diploid, haploid, aneuploid.
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'''polysome''' aggregation of ribosomes.
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'''pore '''L.  ''porus '' = hole, aperture; nuclear pore = aperture in nuclear envelope.
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'''porta hepatis '''L.  ''porta '' = door +  ''hepatis '' = of liver; fissure at hilum of liver; NB. portal vein was vein entering porta hepatis.
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'''porta lienis '''L.  ''porta '' = door + L.  ''lienis '' = of the spleen; fissure at hilum of spleen.
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'''portal ''' adj. L.  ''portare '' = to carry; of a vascular system carrying blood between infundibulum and adenohypophysis = hypothalamohypophyseal portal system. (NB. portal vein is named from L.  ''porta '' = door).
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'''postcapillary venules '''smallest vessels which drain capillary beds into collecting venules.
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'''postsynaptic membrane '''region of membrane on a second cell opposite a synaptic terminal of the first cell; cf. synapse.
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'''prepuce ''' L.  ''praeputium '' = prepuce or covering of glans penis (? from G.  ''pro '' +  ''posthe '' = penis; or ? L.  ''puteo '' = I stink, from smell of smegma, q.v.; thus uncleanliness is figuratively termed  ''praeputia '').
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'''presynaptic membrane '''region of a nerve cell at the synapse of a terminal bouton; cf. synapse.
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'''progesterone '''G.  ''pro '' = before + L.  ''gerere '' = to bear; hormone from corpus luteum preparing the uterus for pregnancy.
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'''prophase''' G.  ''pro '' = before +  ''phasis '' = phase, from  ''phainein '' = to appear, to show; first stage in mitosis of somatic cells.
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'''prostate''' G.  ''pro '' = before + G.  ''istanai '' = to stand, or ? L.  ''statum '' = stood; standing before; male gland at base of ("before") bladder; Aristotle uses  ''prostatai chirsoedeis '' = varicose prostate = seminal vesicles; Herophilus (c. 300 BC) uses  ''prostatai adenoeideis '' = glandular prostate; Galen (c. 180 AD) uses  ''prostatai '' for whole complex of seminal vesicles and prostate, based on animal dissections.
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'''protoplasm '''G.  ''protos '' = first +  ''plasma '' = a thing formed; living matter (Purkinje).
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'''proximal '''L.  ''proxime '' = nearest (to the head, to a source, etc.); opposite to distal, q.v.
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'''psammoma ''' G.  ''psammos '' = sand +  ''oma '' = tumor; laminated concretions found in the pineal gland (cf. brain sand, acervulus)
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'''pseudopodium (-ia) '''G.  ''pseudos '' = false, fraud +  ''podos '' = foot; temporary extension of a cell.
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'''pseudostratified''' G.  ''pseudos '' = false, fraud; simple epithelium where not all apical borders of cells reach lumen, thereby appearing to be stratified.
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'''pseudounipolar''' G. " ; of a sensory ganglion cell, bipolar in embryo, but in adult having one axon which bifurcates into a central and a peripheral branch, the peripheral branch behaving as a dendrite, q.v.; cf. bipolar.
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'''PTAH''' <U>p</U>hospho<U>t</U>ungstic <U>a</U>cid and <U>h</U>aematoxylin stain.
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'''pubes '''L. = signs of manhood; hair of genital region.
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'''pulmonary '''L.  ''pulmo '' = lung.
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'''pulp '''L.  ''pulpa '' = soft, fleshy; central part of a tooth; parts of spleen; central part of a finger.
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'''pulvinar '''L. = a cushioned couch (used by the gods); the raised posterior part of the thalamus, q.v.
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'''punctum lacrimale '''L. = a point + of tears; opening of lacrimal duct at inner canthus of the eye.
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'''pupil '''L.  ''pupa '' = a girl, damsel, a doll (as in puppet); L.  ''pupillae '' = small doll-like images seen mirrored in the eye, led to term  ''pupilla '' for the central aperture of the iris (Cicero).
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'''Purkinje (Purkyne)''', Johannes Evangelista, Ritter von. 1787-1869 Breslau pathologist, Prague physiologist; famous microscopist; early use of microtome; recognized importance of fingerprints (1823); P. cells = largest cerebellar neurones with extensive dendrites (1837); P. cells = conducting heart cells (1845); P. phenomenon = casting shadows of retinal blood vessels.
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'''pyknotic''' G.  ''pyknos '' = thick, close, compact +  ''osis '' = condition; a nucleus with very condensed chromatin; a shrunken nucleus.
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'''pylorus''' G.  ''pyle =  ''a gate + '' ouros '' = a guard; a gate-keeper, a janitor; distal, sphincteric orifice of stomach (Galen, c. 180 AD).
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'''pyramidal cell '''G.  ''pyramis '' = pyramid; cell in the cerebral cortex with a pyramid-shaped soma.
  
  

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A Glossary of Histological and Micro-Anatomical Terms

 Histology Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
Including historical origins and eponyms compiled by Dr Brian Freeman, Department of Anatomy, School of Medical Sciences, revised 2000.
ANAT2241 Support | Histology | Histology Stains | Historic Terminology | Embryology Glossary


Abbreviations: ( ) plural form in brackets, A. Arabic, abb. abbreviation, c. circa =about, F. French adj. adjective, G. Greek, Ge. German, cf. compare, L. Latin, dim. diminutive, NA. Nomina anatomica, q.v. which see, OF. Old French



Pacchioni, Antonio. 1665-1726 Rome & Tivoli anatomist; Pacchionian bodies = arachnoid granulations (1705), q.v.


pachymenix G. pachys = thick + menix = a membrane; the dura mater.


Pacini, Filippo. 1812-1883 Pisa & Florence anatomist; lamellated (onion-like) corpuscles of Vater-Pacini in skin (1840); tendon sheaths.


palate L. palatum = roof of mouth.


palisade L. palus = stake; like a fence of stakes.


palmate folds cf. plicae palmatae.


palpebral adj. L. palpebra = eyelid, from L. palpitare = to move quickly.


pampiniform adj. L. pampineus = full of vine tendrils + forma = shape; a tangled mass of veins in spermatic cord.


pancreas G. pan = all + kreas = edible flesh; a sweetbread (though less of a delicacy than the thymus); intestinal exocrine & endocrine gland.


pancreatic islets small islands or clusters of endocrine cells in pancreas; cf. Langerhans.


panniculus adiposus L. = a little piece of cloth, a rag + L. adeps = fat (adiposus is a L. corruption); the hypodermis (Berengarius, 1524).


Paneth, Josef. 1857-1890 Breslau & Vienna physiologist; P. cells (1887) = eosinophilic cells at base of intestinal crypts of Lieberkühn.


papilla (-ae) L. = a teat, a nipple; a nipple-like projection, e.g., on the tonge (Malpighi, c. 1670; cf. circumvallate, filiform, foliate, fungiform, vallate); duodenal papilla (containing duodenal ampulla); optic papilla; renal papilla (Berengarius, c. 1480-1550).


papillary adj. L. "; of the most superficial layer of the dermis, containing fine collagen fibres immediately under the epidermis; of cardiac muscle fibres that form eminences on the inner surface of the ventricles.


para- G. = beyond, beside, near.


paradidymis G. " + didymos = testicle; remains of mesonephros situated on the spermatic cord above the epididymis= organ of Giraldès, q.v.; also = organ of Waldeyer.


paraganglion (-ia) G. " + ganglion = a swelling; clumps of chromaffin tissue scattered alongside sympathetic nerves in thorax and abdomen; cf. Zuckerkandl.


parakeratin G. " + keras = horn; a type of keratin formed in superficial cells at sites of abrasion and rapid epithelial renewal, e.g., gingiva, tongue, tonsillar crypts, palate.


parametrium G. " + metra = womb, uterus; loose, fatty connective tissue in the broad ligament around uterus.


parathyroid G. " + thyreos = a shield (cf. thyroid gland); gland lying "alongside" the thyroid.


parenchyma G. " + enkeim = to pour in; the essential functional cells of an organ as opposed to its stroma, q.v. (NB. the accent is on the "e", not the "y").


paries (-ities) L. paries = a wall; cf. body wall around a coelom q.v.


parietal adj. L. parietalis = relating to walls; the outer region or wall as opposed to visceral.


paroöphoron G. para = beside + öon = egg + phoros = bearing; minute tubules of the mesosalpinx lying adjacent to the uterine tube, derived from caudal part of embryonic mesonephros.


parotid G. para = beside + otos = of the ear; a salivary gland.


parous L. pario = I bear (children).


pars L. = a part; a part of an organ, or structure, e.g., pars iridica retinae; pars nervosa; pars distalis, etc.


PAS periodic acid & Schiff's reagent; histochemical stain for carbohydrates involving production of aldehyde groups by initial treatment with periodic acid, then reaction of these groups with Schiff's reagent to produce a magenta colour.


pearl 1. a concretion formed around a grain of sand, etc.; 2. a small tough mass of material, e.g., a keratin pearl, an enamel pearl, a pearl of mucus in sputum.


pectinate adj. L. pecten = a comb; musculi pectinati = muscular bands passing forwards from crista terminalis in wall of right atrium (including the crista, resembles a comb).


pedicel L. pediculus = a little foot, dim. L. pes ; stem attached to growing process; pedicles of podocytes in renal glomerulus.


pedicle L. pediculus = a little foot (dim. of L. pes = a foot); stem or connecting stalk of a tumour; bony process connecting the lamina of a vertebra to its body; renal pedicle = renal "stalk".


pellucidum L. per = through + lucere = to shine; translucent; e.g., zona pellucida of ovarian follicle; septum p. of brain.


pelvis L. = a basin.


penicillar adj. L. penicillum = a paint-brush, from L. penna = a feather; branching into many short segments, as in the penicillar arterioles of the spleen


penis L. = a tail.


pepsinogen G. pepis = digestion + gennan = to produce; a precusor of pepsin = enzyme that aids digestion.


peri- G. = around, about.


pericardium G. " + kardia = heart; of two types: visceral (covering the heart) and parietal (lining the pericardial sac).


perichondrium G. " + chondros = granule, gristle, cartilage; connective tissue and cellular layer surrounding cartilage.


pericyte G. " + kytos = hollow vessel; mesenchymal cell adjacent to capillaries.


perikaryon G. " + karyon = nucleus; body of a nerve cell surrounding its nucleus; soma, q.v.


perilymph G. " + L. lympha = clear fluid; a bastard term (from G. & L.) for fluid in bony labyrinth surrounding the membranous labyrinth; cf. endolymph.


perimysium G. " + mys = muscle; connective tissue around a muscle fascicle.


perineurium G. " + neuron = sinew; a lamellated sheath of connective tissue and cells around a nerve fascicle.


periodontal ligament or membrane G. " + odons = tooth; fibro-elastic tissue (including Shapey's fibres) joining the tooth to its alveolar socket in the bone.


periodontium G. " ; all the tissue around the root of a tooth.


periosteum G. " + osteon = bone; fibrous membrane covering bone, attached to bony matrix by Sharpey's fibres.


peripheral nervous system nerves and nerve cells outside the central nervous system; abb. PNS.


peristalsis G. " + stalsis = a contraction, from stellein = to constrict; progressive contractile wave along body tubes (Culpeper, 1655); adj. peristaltic.


peritoneum G. peri = around + teinein = to stretch around; membrane stretched around the lining of the abdominal sac and ensheathing some viscera; adj. peritoneal.


Perls, Max, 1843-1881 German pathologist; Perls' test for hemosiderin using the Prussian blue reaction/stain.


Peyer, Johann Konrad. 1653-1712 Schaffhausen, professor of Logic, Rhetoric & Natural Science; P.'s patches = aggregated lymphatic nodules in terminal ileum (1673).


phagocytosis G. phagein = to eat + kytos = cell + osis = a condition of; process by which a cell engulfs foreign particles, dead material, etc.


phalangeal adj. G. phalanx = a band of soldiers (a Greek army division in battle order); phalangeal cells = sustentacular cells in organ of Corti whose processes extend upwards between the hair cells like fingers; Deiters, q.v.


pharynx G. = throat; adj. pharyngeal (? G. pharanx = a cleft, chasm).


pheomelanin G. phaios = dusky red + melas = black; pigment found in red hair.


phlegm G. phlegma = thick mucus; one of four humours of early physiology; thought to be a discharge from brain; cf. pituitary.


Phloxine red cytoplasmic dye.


photoreceptor G. phos = light + L. recipio = I receive; bastard term for light-sensitive cells in retina.


physic G. physikos = natural; the art of medicine.


pia mater L. pius = soft, faithful (L. pietas was one of the cardinal virtues) + mater = mother; delicate vascular membrane which adheres to surface of brain and spinal cord, faithfully following their contours.


picric acid a yellow dye.


pilomotor L. pilus = a hair + motor = mover; causing hair movement; cf. arrector pili.


pineal L. pinea = pine cone; cone-shaped gland of the brain; cf. conarium.


pinocytosis G. pinein = to drink + kytos = cell + osis = a condition of; process by which a cell takes in droplets of fluid.


pituitary L. pituita = phlegm, snot; gland at base of brain thought to be responsible for nasal secretion, via perforations in cribriform plate of ethmoid (Vesalius, c. 1560).


placenta L. = a flat cake, from G. plax - = flat- ; (Ge. Mutterkuchen = "mother-cake" = placenta).


plasma G. = a thing formed; liquid component of lymph, blood; NB. plasma membrane = cell membrane.


plasmodium G. " + -oeides = like; a continuum of protoplasm in which many nuclei are embedded, e.g., placental plasmodium = syncytiotrophoblast.


plasmolysis G. " + lysis = solution; shrinkage of a cell due to osmotic pressure.


platelet OF. plate = flat; small, non-nucleated discoids in circulating blood derived from fragmentation of megakaryocytes.


pleomorphic G. pleon = more + morphe = form; varying in shape and size.


pleura (-ae) G. = rib, side; serous membrane covering lungs and lining thorax; parietal and visceral pleurae.


plexus (-i) L. = a braid; a woven network of linear structures, especially nerves.


plica (-ae) a corruption from L. plicare = to fold; in13th century a scalp infection endemic in Poland was called plica polonica (Polish plait); any kind of fold.


plicae circulares L. = circular folds; actually transverse folds that are not circular in small intestine = valves of Kerckring, q.v.


plicae palmatae L. " + palmatae = like palm trees; flat mucosal folds like palm fronds in uterine cervical canal.


podocyte G. podos = foot + kytos = hollow vessel (cell); cell in renal glomerulus with many feet (foot processes) and pedicels.


-poiesis G. = making or producing; suffix as in haemopoiesis, leucopoiesis.


polar body the smaller daughter nucleus of a fertilised dividing ovum.


polkissen Ge. = pole cushion; extraglomerular mesangial cells at vascular pole.


polychromatophilic G. polys = many + chroma = colour + philein = to love.


polymorphonuclear (abb. polymorph) adj. G. " + morphe = form; having a nucleus with different shapes (multiple lobes), e.g., a neutrophilic leucocyte.


polyploid G. " + -oeides = form of; G. = manifold; having several sets of chromosomes; cf. diploid, haploid, aneuploid.


polysome aggregation of ribosomes.


pore L. porus = hole, aperture; nuclear pore = aperture in nuclear envelope.


porta hepatis L. porta = door + hepatis = of liver; fissure at hilum of liver; NB. portal vein was vein entering porta hepatis.


porta lienis L. porta = door + L. lienis = of the spleen; fissure at hilum of spleen.


portal adj. L. portare = to carry; of a vascular system carrying blood between infundibulum and adenohypophysis = hypothalamohypophyseal portal system. (NB. portal vein is named from L. porta = door).


postcapillary venules smallest vessels which drain capillary beds into collecting venules.


postsynaptic membrane region of membrane on a second cell opposite a synaptic terminal of the first cell; cf. synapse.


prepuce L. praeputium = prepuce or covering of glans penis (? from G. pro + posthe = penis; or ? L. puteo = I stink, from smell of smegma, q.v.; thus uncleanliness is figuratively termed praeputia ).


presynaptic membrane region of a nerve cell at the synapse of a terminal bouton; cf. synapse.


progesterone G. pro = before + L. gerere = to bear; hormone from corpus luteum preparing the uterus for pregnancy.


prophase G. pro = before + phasis = phase, from phainein = to appear, to show; first stage in mitosis of somatic cells.


prostate G. pro = before + G. istanai = to stand, or ? L. statum = stood; standing before; male gland at base of ("before") bladder; Aristotle uses prostatai chirsoedeis = varicose prostate = seminal vesicles; Herophilus (c. 300 BC) uses prostatai adenoeideis = glandular prostate; Galen (c. 180 AD) uses prostatai for whole complex of seminal vesicles and prostate, based on animal dissections.


protoplasm G. protos = first + plasma = a thing formed; living matter (Purkinje).


proximal L. proxime = nearest (to the head, to a source, etc.); opposite to distal, q.v.


psammoma G. psammos = sand + oma = tumor; laminated concretions found in the pineal gland (cf. brain sand, acervulus)


pseudopodium (-ia) G. pseudos = false, fraud + podos = foot; temporary extension of a cell.


pseudostratified G. pseudos = false, fraud; simple epithelium where not all apical borders of cells reach lumen, thereby appearing to be stratified.


pseudounipolar G. " ; of a sensory ganglion cell, bipolar in embryo, but in adult having one axon which bifurcates into a central and a peripheral branch, the peripheral branch behaving as a dendrite, q.v.; cf. bipolar.


PTAH phosphotungstic acid and haematoxylin stain.


pubes L. = signs of manhood; hair of genital region.


pulmonary L. pulmo = lung.


pulp L. pulpa = soft, fleshy; central part of a tooth; parts of spleen; central part of a finger.


pulvinar L. = a cushioned couch (used by the gods); the raised posterior part of the thalamus, q.v.


punctum lacrimale L. = a point + of tears; opening of lacrimal duct at inner canthus of the eye.


pupil L. pupa = a girl, damsel, a doll (as in puppet); L. pupillae = small doll-like images seen mirrored in the eye, led to term pupilla for the central aperture of the iris (Cicero).


Purkinje (Purkyne), Johannes Evangelista, Ritter von. 1787-1869 Breslau pathologist, Prague physiologist; famous microscopist; early use of microtome; recognized importance of fingerprints (1823); P. cells = largest cerebellar neurones with extensive dendrites (1837); P. cells = conducting heart cells (1845); P. phenomenon = casting shadows of retinal blood vessels.


pyknotic G. pyknos = thick, close, compact + osis = condition; a nucleus with very condensed chromatin; a shrunken nucleus.


pylorus G. pyle = a gate + ouros = a guard; a gate-keeper, a janitor; distal, sphincteric orifice of stomach (Galen, c. 180 AD).


pyramidal cell G. pyramis = pyramid; cell in the cerebral cortex with a pyramid-shaped soma.




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